Pond Liners

Don't even consider using a pond liner if it doesn't come with a long term warranty. All of the liners described here come with a 20 year warranty. It states that the liner will not prematurely deteriorate because of weathering within the 20 year period. The sun's ultraviolet rays are the primary culprit in the deterioration of most liners. A properly built pond, with boulders and gravel covering the liner, will protect the liner from ultraviolet rays. Further extending its lifespan well beyond 20 years.

It is important to also determine whether the liner you choose is safe for any fish that may inhabit the pond. According to Andy Furman, production manager of Carlisle Syntec, Aquascape's supplier of fish safe pond liners, "a fish safe liner is given a stamp of approval by the manufacturer that guarantees the membrane is chemically compounded to be fish safe, and that this is verified by testing to ensure that it is not toxic to fish."

Advantages: EPDM is extremely flexible. This comes in handy when working with the irregular twists, turns, and shelves commonly found in a pond or stream. EPDM easily drapes into the excavated area and conforms to all of the nooks and crannies in the application.

Limitations: Size is a limitation when specifying EPDM for a job. The largest roll size manufactured is 50' x 100'. Seeming EPDM can be difficult. You may have noticed that Aquascape offers seaming supplies for EPDM rubber.

Why not just seam two large sections together?

• Weather conditions have to be perfect in order to properly complete a seam. Moisture, such as rain or cold, damp conditions can affect seam quality.
• You need to have a good, flat foundation in order to perform the seam.
• The seam tape can be a real mess. It wants to stick to everything, including you! Not to mention that seaming is tedious and time consuming.
• We do seam EPDM liner in the field, but we don't seam large sections of liner together. We usually only seam short sections of liner together, such as where a deep stream liner meets the pond liner.

40 mil Polypropylene
There are a couple of other pond liner alternatives to choose from if your pond requires a liner larger than 50' x 100'. One of them is 40 mil polypropylene.

Advantages: 40 mil polypropylene is actually more durable and puncture resistant than 45 mil EPDM. If the job requires a liner larger than 50' x 100' the factory will custom make the liner for your project. This custom sizing takes about two weeks, so you need to allow for that in scheduling the project. The liner can be made in sizes over four times as large as EPDM. The other great attribute of a polypropylene pond liner is its ability to be seamed or "welded" together very easily. This comes in very handy in the field. The process is as simple as using a standard heat gun that can be purchased at any hardware store. The pond liners are overlapped and welded, or melted together. This technique takes a little practice, but once learned, can be easily applied in the field.

Limitations: Flexibility and Cost. Polypropylene, unfortunately, is not nearly as flexible as EPDM. This limits its use to larger projects. Trying to use polypropylene on the typical small residential backyard pond would be difficult and the bends and curves would be aggravating. Polypropylene is a few cents per square foot more expensive than EPDM. This can add up quickly on large projects. Its performance and durability, however, are well worth the extra dollars.

30 mil Polythylene
For large projects that are under budget constraints, we turn to our third choice for pond liners, 30 mil polythylene.

Advantages: The only real advantage of polythylene is its cost. It's about half the cost of polypropylene and EPDM. As with the polypropylene liner, it too can be manufactured to custom fit your application.

Limitations: Cheaper isn't always better, and in this case, you get what you pay for. Polythylene is not nearly as flexible as EPDM or polypropylene. It is a "plastic" type liner and can be stiff to work with. Polythylene does not hold up as well with the beating that it takes from the placement of large stones in the pond. Basically, you have to be a little more careful! Polythylene cannot be seamed together without expensive welding equipment. Typically, seaming of polythylene is subcontracted out to a specialist who has the proper equipment and training. We have used polythylene with success on a number of large scale installations over the last eight years, but it was not until the 40 mil polypropylene pond liner was introduced to us 2 years ago that we switched away from polythylene. If you can't fit the higher cost of polypropylene into a large-scale pond budget, you can choose polythylene as a less expensive alternative.

Pound for Pound ... Something to Consider

When it comes to building large ponds that require 40 mil polypropylene or 30 mil polythylene liners, one needs to factor in the weight of the liner. Pond liners for large 1/2 acre ponds can easily weigh a couple of tons. This is an obstacle that is often overlooked, but with a dozen or so laborers and a little sweat, the liner can be pulled into an excavated pond.